A number of months ago, my startup, Iodine, had the kind of moment that all startups dream about. We were invited by Apple--yes, that Apple--to partner on the launch of an app framework for health, called CareKit.

For a software startup, it doesn't get much better. Here we are, a little, nine-person shop, getting early access to Apple's developer tools, and there was Apple helping us make the best app we could with its engineers. It was a rare invitation to peek behind the curtain of the biggest technology company--hell, one of the biggest companies--on the planet. And it led to a crescendo of media coverage and tens of thousands of app downloads.

It would be more than a little tacky to complain about such an opportunity. But it would also be more than a little naive not to recognize the big risks that come along for a ride like this. We managed to avoid the worst, and there's a valuable lesson in that. Partnering with a company like Apple, we had to make sure our objectives didn't get lost and that our day in the sun didn't leave us a little too exposed.

The whole thing started in a very Apple-y way, which is to say, with meetings where we explained everything we were doing with our  Start app (it's a mental-health app that helps people take control of their depression) and didn't learn much in return. But eventually, we got the wink and nudge that there was something big cooking. And boy, did we want to be part of the program.

For a month, we turned all hands at Iodine to reworking our app to take advantage of CareKit, building Apple's framework into our code. Then we got the official, top-secret launch date, and went on a mad dash to debug our code, so the app could go live on the right day.

Launch day at Apple's Cupertino, California, headquarters was a perfectly choreographed extravaganza of wall-to-wall media coverage, much of it featuring our Start app. For an added boost, Apple put the CareKit apps (there were two other companies in on the build as well) on the App Store homepage.

Then, three things happened all at once. First, we had a massive number of downloads, which was great. Second, there was welcome interest from possible new partners, including investors and health care systems. And third, there were the inevitable bugs--little, pesky problems that turn up only when 5,000 people begin simultaneously testing your product. That's a good problem to have.

Thankfully, we had made sure to prepare for all three. Our terrific PR team had a plan ready to go, and quickly turned that deluge of coverage into several more stories. My co-founder and I spent most of the next two days networking on email to leverage the press into something more tangible. And our engineers ably triaged several technical issues that could've turned those thousands of new users into thousands of unhappy users.

The key to making the most of that day was preparation. On launch day, we had to play defense and offense at once. And every hour that ticked by was another hour past the fanfare and closer to reality. A couple of days later, everything had pretty much returned to normal--but we hope we took enough advantage of that moment to make something more of Iodine.

Every startup chases its own version of Apple, trying to land that one big deal or partnership. And here we are, the dog that actually caught the bus. But unlike a dog, we had to know what to do once we got our teeth into it.

From the July/August issue of Inc. magazine